Year	% of total
1992	14.879589235127478
1993	14.67303939532753
1994	15.416631384812765
1995	14.228006870107047
1996	14.536064383777813
1997	14.625097363570799
1998	16.51568449377733
1999	17.019858865564984
2000	14.704321669237638
2001	15.71742177314211
2002	16.733993925588457
2003	16.586178219434714
2004	17.437856448476992
2005	17.873569166666666
2006	17.316388888888888
2007	17.47037935776106
2008	18.234266756825292
2009	18.77865521273725
2010	17.461138418327042
2011	17.56181744458461
2012	17.63526919846972
2013	17.981580023364486
2014	19.36249523809524
2015	19.743987918399682
2016	19.707540346101496